Method for regenerating solid catalyst

ABSTRACT

A process for regenerating a solid catalyst which has been used for producing propylene oxide through an epoxidation reaction of propylene with an organic peroxide in a reactor packed with the solid catalyst, which comprises allowing a liquid to flow through the catalyst packed in the reactor at a temperature not lower than the maximum reaction temperature of the epoxidation reaction.  
     According to the present invention, a catalyst can be regenerated with extremely high efficiency without taking the catalyst to be regenerated out of the reactor.

TECHNICAL FIELD

[0001] The present invention relates to a process for regenerating asolid catalyst. More particularly, the present invention relates to aprocess for very efficiently regenerating a solid catalyst used forproducing propylene oxide through epoxidation of propylene with anorganic peroxide in a reactor in which the solid catalyst is packed.

BACKGROUND ART

[0002] It is publicly known to produce propylene oxide by epoxidation ofpropylene with an organic peroxide in a reactor in which the solidcatalyst is packed. But, the activity of the catalyst deteriorates withtime used. The catalyst in which the activity has deteriorated, requirerecovery of the activity by changing to a new one or regenerating it.

DISCLOSURE OF THE INVENTION

[0003] Under such situations, the subject to be solved by the presentinvention is to provide a process for regenerating a solid catalyst,which permits the regeneration of the catalyst with extremely highefficiency, without the needs for taking the catalyst to be regeneratedout of the reactor when the solid catalyst used for producing propyleneoxide by epoxidation of propylene with an organic peroxide in thereactor in which the solid catalyst is packed.

[0004] Namely, the present invention relates to a process forregenerating a solid catalyst which has been used for producingpropylene oxide through an epoxidation reaction of propylene with anorganic peroxide in a reactor packed with the solid catalyst, whichcomprises allowing a liquid to flow through the catalyst packed in thereactor at a temperature not lower than the maximum reaction temperatureof the epoxidation reaction.

BEST MODE FOR CARRYING OUT THE INVENTION

[0005] In the present invention, the solid catalyst to be regenerated,is a solid catalyst which has been used for producing propylene oxidethrough epoxidation of propylene with an organic peroxide in a reactorpacked with the solid catalyst.

[0006] As the solid catalyst, it is preferable to use atitanium-containing silicon oxide solid catalyst, and as thesecatalysts, so-called Ti-silica catalysts containing Ti chemically bondedto silicon oxide, are preferable. For example, there are illustrated aproduct in which a Ti compound is supported on silica carrier, a productin which a Ti-compound is mixed with silicon oxide by a co-precipitationmethod or a sol-gel method, a zeolite compound containing Ti, and thelike. As a shape of the solid catalyst, any shape such as powder,granule, particle, mass or the like can be adopted, but, it ispreferable to use a catalyst having several hundreds of micron meters toseveral tens of micron meters in size taking account of separability ofa reaction liquid and a pressure loss of a reactor. Further, when acatalyst is primarily powder, it is preferable to use after making itlarge in size to some extent through molding.

[0007] As the organic peroxide to be reacted with propylene, cumenehydroperoxide, ethylbenzene hydroperoxide and t-butyl hydroperoxide canbe exemplified.

[0008] As the reactor, a slurry-type reactor, a fixed bed reactor andthe like can be used. In a case of a large scale operation, it ispreferable to use a fixed bed reactor. Further, the reaction can becarried out by a batch process, semi-batch process or continuousprocess. The epoxidation temperature is usually 0 to 200° C., andpreferably 25 to 200° C. The pressure may be a pressure enough to keep areaction mixture to a liquid state, and it is advantageously 100 to10,000 kPa in usual.

[0009] The regeneration process of the present invention is aregeneration process of a solid catalyst, which comprises allowing toflow a liquid through a catalyst packed in a reactor used for anepoxidation reaction at a temperature of not lower than the maximumreaction temperature in the epoxidation reaction. Namely, theregeneration is carried out without taking the catalyst out of thereactor used for the epoxidation reaction, therefore it is extremelyhigh efficient. The temperature during the regeneration is a temperaturenot lower than the maximum reaction temperature in the epoxidationreaction, preferably a temperature higher by 5° C. or more than themaximum reaction temperature, further preferably a temperature higher by10° C. or more than the maximum reaction temperature.

[0010] When the temperature during regeneration is lower than themaximum reaction temperature of epoxidation, an effect of regenerationbecomes insufficient. Herein, there is a case of elevating gradually theepoxidation temperature for conpensating a deterioration of the activitywith time during the reaction, and the maximum reaction temperaturemeans that in that case.

[0011] Further, the temperature at regeneration is preferably 300° C. orless from the viewpoint of durability of the catalyst. In addition,herein, the reaction temperature is a temperature of a catalyst layer,and when there is temperature distribution in the catalyst layer, it isa temperature at the lowest part in temperature.

[0012] As the liquid to be flown at regeneration, a liquid used in thereaction system is preferable from the viewpoint of prevention ofcontamination of a product and the system, and the epoxidation reactionliquid, cumene, liquid propylene ant the like can be illustrated, andliquid propylene is the most preferred. Herein, the liquid propylenealso includes a super critical fluid of propylene. AS the regenerationprocess, a liquid may be passed through the catalyst, and as preferableconditions, a LHSV of 0.5 h⁻¹ or more and a flow time of 1 hour or moreare mentioned.

EXAMPLE EXAMPLE 1

[0013] 5 cc of a silicon oxide catalyst containing 1.3% by weight of Ti(average particle diameter 0.9 mm, molded article) was packed in areactor, and a cumene solution having a cumene hydroperoxideconcentration of 25 to 35% by weight and propylene were allowed to flowto conduct an epoxidation reaction. The reaction was initiated at a LHSVof 18 h⁻¹, reaction pressure of 5.5 MPaG and reaction temperature of 80°C., and the temperature was gradually raised with deterioration of theactivity. The reaction temperature became 110° C. after 1800 hours.Next, for regeneration operation, the feed of the cumene solution wasstopped, then the temperature of the catalyst layer was elevated to 120°C. and only liquid propylene was allowed to flow through the catalystlayer at a rate of 0.3 g/minute for 18 hours. After liquid propylene wasflown, the epoxidation reaction was carried out by allowing to flow a 25weight % cumene hydroperoxide solution and propylene at 110° C., again.The result is shown in Table 1.

Comparative Example 1

[0014] An epoxidation reaction was carried out in the same manner as inExample 1 except that, as regeneration operation, the temperature atwhich only liquid propylene was flown, was 105° C. The result is shownin Table 1.

Example 2

[0015] 5 cc of a silicon oxide catalyst containing 1.3% by weight of Ti(average particle diameter 0.9 mm, molded article) was packed in areactor, and a cumene solution having a cumene hydroperoxideconcentration of 25 to 35% by weight and propylene were allowed to flowto conduct an epoxidation reaction. A LHSV of 18 h⁻¹ and reactionpressure of 5.5 MPaG were adopted, and after the reaction of 1500 hours,the reaction temperature was 110° C. Next, for regeneration operation,the feed of the cumene solution was stopped, then the temperature of thecatalyst layer was elevated to 130° C. and only liquid propylene wasallowed to flow through the catalyst layer at a rate of 0.7 g/minute for20 hours. After liquid propylene was flown, the epoxidation reaction wascarried out by allowing to flow a 25 weight % cumene hydroperoxidesolution and propylene at 110° C., again. The result is shown inTable 1. TABLE 1 Comparative Example 1 Example 1 Example 2 Maximumtemperature 110 110 110 in epoxidation ° C. Regeneration 120 105 130temperature CMHP conversion *1% Before regeneration 54.8 54.8 42.4 Afterregeneration 60.8 54.8 73.9

[0016] Industrial Applicability

[0017] As described above, according to the present invention, there canbe provided a process for regenerating a solid catalyst, which permitsthe regeneration of the catalyst with extremely high efficiency, withoutthe needs for taking the catalyst to be regenerated out of the reactorwhen the solid catalyst used for producing propylene oxide byepoxidation of propylene with an organic peroxide in the reactor inwhich the solid catalyst is packed, is regenerated.

1. A process for regenerating a solid catalyst which has been used forproducing propylene oxide through an epoxidation reaction of propylenewith an organic peroxide in a reactor packed with the solid catalyst,which comprises allowing a liquid to flow through the catalyst packed inthe reactor at a temperature not lower than the maximum reactiontemperature of the epoxidation reaction.
 2. The process according toclaim 1, wherein the temperature at which the liquid is flown, is higherby 5° C. or more than the maximum temperature in the epoxidationreaction.
 3. The process according to claim 1, wherein the catalyst is atitanium-containing silicon oxide solid catalyst.
 4. The processaccording to claim 1, wherein the liquid is propylene.
 5. The processaccording to claim 1, wherein the organic peroxide is cumenehydroperoxide.